JPS61120837A - Production of closed cell phenol resin foam - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an improved closed cell phenolic resin foam, and more particularly, to an improved closed cell phenolic foam having high wall strength and substantially no microvoids in the cell walls; The present invention relates to a method for manufacturing the foam.

PRIOR ART Phenolic polymers have been known for a long time, and there is also much prior art regarding cellular materials made from these polymers, which are even more common as foam materials. Such foams are produced by mixing the reactants in the presence of a blowing agent that produces a foam that is subsequently cured. However, most of the prior art relates to what is known as open-celled phenolic resin foams, the methods of which are well known for their manufacture. Even better known is the use of fluorinated hydrocarbon blowing agents with low thermal conductivity. Most of the well-known cellular materials made from phenolic polymers have initial problems, especially in that they are insulating products with insufficient thermal conductivity and have too high a porosity. It is inferior in that it exhibits other properties and also exhibits an undesirable increase in thermal conductivity over time.

A more desirable product is known as closed cell phenolic foam, but it is difficult to manufacture. There has never been a formulation that makes a difference between closed cell foams compared to open cell foams. The initial thermal conductivity with closed cell foams is significantly better than with open cell foams for obvious reasons.

However, even with closed cell foams, the presence of microvoids in the cell walls increases the rate of diffusion of air into the cells, displacing gases with low thermal conductivity in the cells.

In order to achieve the maximum benefits obtained from the closed cell foam, two properties are maintained, namely to preserve the low thermal conductivity of the product by preventing the diffusion of air into the cell structure. I have to do it. There should be no microvoids or microperforations in the cell walls, and the cell walls should have high strength.

Below, several prior art patents relating to closed cell phenolic resin foams are discussed.

U.S. Patent No. 4 by qu smer
．． No. 304,758 relates to closed cell phenol-aldehyde resin foams and methods of making the same. In the method according to that patent, the internal temperature of the foam material during curing is kept above the boiling point of the blowing agent and below 100°C, which is sufficiently low to maintain the closed cell structure as the foam is cured. It is. The internal temperature is adjusted by using a resol resin that generates sufficiently little heat during the reaction and by using an appropriate amount of acid catalyst. First, the resin used is dehydrated to remove most of the water. i.e. the total water content is less than 10% by weight, often even lower, e.g.
Leave it drip-free. Tests are performed to determine the reactivity of the resin and to see if it meets the requirements. The blowing agents, acid catalysts and surfactants used are those conventionally used, the acid catalyst usually being used in an amount of about 0.5 to 5% by weight. Reaction times are expected to be 15 minutes or longer given the ratio of acid catalyst suitable for use.

D'Alessandro cx
), U.S. Pat. No. 3,589,094, relates to a closed cell phenolic resin foam having a fine cell size. This is obtained by foaming phenol-formaldehyde containing less than 10% water with polyhalogenated fluorocarbons. This appears to be an essential requirement and the real focus of the patent. It should be noted that there are no interstitial voids or holes in the six sections of the foam. The acid catalyst used is conventional and the amount used is not critical.

Beale et al. U.S. Patent No. 4
．． No. 133,931 relates to closed cell phenolic resin foams made by a manufacturing process using special surfactants. A commonly used catalyst is usually added to the weight of the foam material (
It is used in an amount of 15 to 200% by weight. The surfactant is
It is a branched nonionic material with a hydroxyl number of less than 50 by capping excess hydroxyl groups.

US Pat. No. 4,247,413 to Beale et al. K. is a divisional application of the patent discussed above. Of course, the patent relates to closed cell phenolic resin foams, but also includes the use of special surfactants.

U.S. Patent No. 4,353 by Smith K.
, 994 relates to closed cell phenolic resin foams, which are produced by reaction of levafurfuryl alcohol compound topendyl ether phenolic resin. Conventional acid catalysts are used.

U.S. Patent No. 4.16 by Sefton
No. 5,413 relates to improved phenol-aldehyde foam condensates, but apparently to open cell foams. The patent relates to foaming the resin in the presence of N-methyl-2-pyrrolidone to obtain a more uniform cell structure. Commonly used catalysts and blowing agents are used. Although the nuclear patents clearly relate to open cell foams, the product is described as being substantially free of ruptures, voids or boo-holes, and thus having a more uniform cell structure.

Apparently, this is due to the inclusion of N-methyl-2-pyrrolidone, which is defined in that patent. This material is used in an amount of about 1125 to about 5.0 parts per hundred parts resin (PHR).

One drawback of the prior art described above is that when the resin is dehydrated to a low water content, the resin is difficult to handle due to the high viscosity of the remaining material. Another drawback of the prior art is the long reaction time. As mentioned above, it is also desirable to minimize voids in the cell walls as this relates to the stability of the resin's thermal conductivity. Naturally, this value is a very important property of insulating materials. In one of the above-mentioned patents, an additive to the foam causes the disappearance of most of the voids, but the patent describes a method for obtaining a foam with a very high percentage of closed cells. It doesn't give any suggestion.

PROBLEM TO BE SOLVED BY THE INVENTION The present invention provides a very high quality closed cell phenol having a minimum closed cell content of 75 cells, usually 80 cells, and often 85 cells or more. This invention relates to an improved method for obtaining sexual forms. Furthermore, the foams so produced are substantially free of perforations or microvoids and have high wall strength and highly improved thermal conductivity stability. Furthermore, this method is suitable for keeping foaming and curing times as short as possible.

SUMMARY OF THE INVENTION The present invention therefore provides an entire method that relies on a combination of factors. One of the combinations of factors is to control the moisture content of the system. That is, the moisture content of the resin and catalyst is controlled to less than about 14% of the total system. second combination
The feature of ffJ is that the system is maintained homogeneous by using a lipophilic soluble catalyst. Second, for proper operation to occur, a minimum amount of surfactants is required, and these surfactants must be effective in the temperature range from 0 to 100°C. Finally, and most importantly, , the foaming is carried out in the presence of butyrolactone or other lactones as additives.

By using this combination of factors in the production of phenolic foam materials, K stability is significantly improved and faster foaming processes are possible.

The phenol-aldehyde resins that can be used in the process of the invention are usually liquid, water-soluble or water-emulsifiable resol-type resins known as A-stage resins. These resins are phenols and aldehydes.

Preferably, it is produced by reacting with formaldehyde in an alkaline medium in equimolar amounts or using formaldehyde in excess. This resol is soluble in alkalis, alcohols, and to some extent in water.This resol mainly consists of a complex mixture of phenolic alcohols exhibiting a relatively high hydroxyl group content.

Aqueous phenol-formaldehyde resins can be prepared by reacting phenol and formaldehyde under controlled conditions with a determined excess of free formaldehyde. Here, the resin is prepared by reacting phenol and formaldehyde in a certain critical proportion in the presence of a basic catalyst up to a certain end point less than a certain weight of free phenol. O-phenol formaldehyde resins can also be produced in a two-step process in which the first step is carried out under novolak-forming conditions and the second step is carried out with a basic catalyst under resol-forming conditions.O-resole resins Many compounds can be used for the phenol or aldehyde used to produce the phenol or aldehyde.

These compounds may include both phenol itself and its congeners such as cresol and xylenol, or mixtures thereof.

Aldehydes include formaldehyde, acetaldehyde, furfural and other aldehydes and mixtures thereof. Aldehyde-forming compounds such as paraformaldehyde, hexamethylenetetramine, methanol, trioxane, tetraoxymethylene, etc.
It can be used. These materials, other than phenol and formaldehyde themselves, usually react at a slow rate;
Preferred materials for use in accordance with the present invention are phenol-resole resins derived from phenol and formaldehyde. Typically 1 The ratio of phenol to formaldehyde in the resole resin is standard practice in the art;
The ratio is about 1:i,4 to 1:1.8, but this range is not limiting and other resol resins can easily be used.

According to the invention, before the resin is mixed with the other components of the foam-making vessel, the moisture is removed, if desired, by evacuation or vacuum stripping in order to comply with all customary limits for moisture content. Conventional phenol formaldehyde resol resins typically contain about 5 to 20 parts by weight of water, so removal of water may not necessarily be required.

When the water content is about 9 yen, the viscosity of the resin is about 25.000
CI)ST'ab, but when the water content is about 5 parts, the viscosity is about 100,000 to 150,000 c'ps.

For the foaming process to be successful and for obvious technical reasons, the resin must be easily handled and processed. Several possibilities exist for handling viscous substances such as those mentioned above.

Firstly, it is possible to heat one resin, but this is limited in terms of applicability, and heating does not reduce the viscosity to very low values. moreover.

Another possibility is to use pumps and mixing equipment that are highly designed to handle very high viscosity resins, resulting in problems with resin stability and difficulty in controlling the process. However, the disadvantage of this is clearly the high cost of the device.

Additionally, a solvent can be added to reduce the viscosity of the resin.
About 10 to 1 cps based on the weight of the resin.
The viscosity was increased to 10,000 by adding 50% of solvent.
It can be reduced to the order of ~20,000 cps and is even easier to handle. When large amounts of water are removed from the resin, either the solvent is added first and the water subsequently distilled off, or the water is distilled off first as already indicated.

In embodiments according to the invention, the resin can be dissolved in a solvent before or after removing the water so that the water content is about 14 inches or less, as indicated above.

It has already been mentioned that the process according to the invention is carried out in the presence of butyrolactone or other lactones as additives. Here, the water content of the system can actually be raised above about 14 wts by using an increased proportion of lactone, but this is undesirable because it results in higher costs. The most practical method is to add the lactone to the resin, or use it as part of the solvent in which the resin is dissolved, or mix it with the catalyst.
Although the resin can be dissolved in the lactone, which itself is a solvent and an additive.

This adds to the cost of the materials used.

However, the lactone is preferably mixed with the resin immediately before use to influence the shelf life of the resin. Therefore, 0-butyrolactone, which can be mixed with the catalyst, is most preferred from cost, commercial availability, boiling range, and other considerations.

As indicated above, these are not the only materials that can be used as additives. Any compound of the lactone class is suitable for this purpose. Other examples include 5-valerolactone and bromobutyrolactone.

Butyrolactone or other lactone may be used at 1 phr, depending in part on the viscosity required, but as practical
It is added to the system at a concentration of 1 to 10 phr. Although this range is not limited, in order to make the phenolic foam produced by the present invention even better,
Usually an amount of at least about 3 phr is required.

Other solvents that can be used in combination with lactones to dissolve the resin include water.

Any aprotic solvent that dissolves in the resin and has a boiling point above 100°C can be used to dissolve the resin. Examples include polyhydroxy compounds such as ethylene glycol, propylene glycol, and glycerin. The amount of solvent or solvent mixture used for this ranges from about 5 to 25% by weight,2 depending of course on the solubility of the resin and the desired viscosity for further handling the resin as well as the water content of the resin. . With these criteria in mind, higher or lower amounts can be applied at will.

Any acid catalyst that promotes crosslinking and foaming reactions can be used in the process of the present invention, provided the catalyst is soluble in the resin. Examples include acetic acid, phosphoric acid and sulfonic acids, especially aromatic sulfonic acids such as benzenesulfonic acid, toluenesulfonic acid and xylene sulfonic acid. When acetic acid or phosphoric acid is used, it can be used as it is in the absence of water, or it can be used after being dissolved in water or a solvent together with other acids mentioned above.

Solvents used for such purposes can be the solvents mentioned above used for the resins.Although lactones can also be used as solvents, this usage is less practical as it increases the cost of the product.

The solvent is preferably ethylene glycol, but other common solvents such as dimethyl sulfoxide and dimethyl formamide can also be used.

The catalyst must be resin soluble to prevent phase separation and maintain a homogeneous mixture during the reaction. The preferred acid catalysts used are aromatic sulfonic acids such as toluene sulfonic acid or xylene sulfonic acid dissolved in ethylene glycol or dimethyl sulfoxide.

The amount of acid catalyst used will depend on its acidity and optimum expansion rate, but can of course be determined by a person skilled in the art. However, the amount is typically 3 to 5
0 phr, preferably 10 to 15 phr, as required in other cases carried out in the absence of lactone as an additive, since the catalyst content also depends to some extent on the type of solvent used. There are also somewhat fewer children.

Surfactants required for the present invention include:

Any surfactant conventionally used in the production of phenolic foams may be used as long as it is effective in the temperature range from 50° to 100°C. Suitable surfactants that can be used in the method of the invention include silicone/ethylene oxide/propylene oxide copolymers, alkoxysilanes, polysilylphosphonates, polydimethyl/siloxanes and polydimethylsiloxane polyoxyalkylene copolymers and those skilled in the art. Also included are any other surfactants known to be useful in the preparation of phenolic foam resins. A preferred surfactant is Dow Corning C
Polydimethylsiloxane-polyoxyalkylene block copolymers such as those obtained under the trademark "DC-193" from G.
RBXOL is an ethoxylated castor oil commercially available under the trade name Refsol "RBXOL" from Oration).

The amount of surfactant used is unimportant as long as the minimum ratio is followed.The minimum ratio is 2 phr for any type of surfactant. Above that the amount is unimportant. but may range up to about 10 phr, with about 5 to 5 phr being preferred.

Various types of blowing agents can be used in the process according to the invention, provided that they have a low thermal conductivity and, of course, a low boiling point.

Some examples include polyhalogenated saturated fluorocarbons, halogenated hydrocarbons, particularly fluorocarbons, hydrocarbons, or mixtures thereof having boiling points from about -40<0>C to about 93<0>C at atmospheric pressure. Some examples include chlorinated and fluorinated hydrocarbons such as chloroform, methylene chloride, trichlorofluoromethane, tetrafluoromethane, 1,1,2-trichloro-1,2,,l-)lifluoroethane, monochlorodifluoro Methane, dichlorodifluoromethane, 1,1-
Dichloro-1,2,2,2-tetrafluoroethane, 1
．． 2-dichloro-1,1,2,2-tetrafluoroethane, 1.1', 1-trichloro-2,2,2-)lifluoroethane, 1,2-difluoroethane, promotrifluoromethane, 1,1° 2.2-tetrachloro-1,2
-difluoroethane, 1.1,1.2-tetrachloro-
Mention may be made of 2,2-difluoroethane or mixtures thereof. However, preferred polyhalogenated fluorocarbons are those commercially available from EI Dubon Dunemoul & Co. under the FREON tv trademark, particularly trichlorofluoromethane and 1,1,2-trichloro-1°2.2-) respectively. FREON i 1 and FREON which are refluoroethane
It is 115. The amount of blowing agent used in accordance with the present invention is not critical and may vary from about 10 to about 50 phr, preferably from 10 to 20 phr.

The method of addition of reactants for foaming and polymerization is not critical as long as the reaction mixture is homogeneous; a shear mechanical mixer is preferred; resin, surfactant, and blowing agent may be mixed and then the catalyst added. In this case, the lactone may be added together with the resin or with the catalyst.

After foaming has occurred, preferably about 60 to 100°C
The mixture is cured by heating to . When the catalyst is mixed with other ingredients, the mixture begins to cream, and when nucleation occurs during the cream stage, this is the starting point for foaming.0 If butyrolactone is present in the composition as a butyrolactone, it is ideal for manufactured products. The total processing time to obtain the desired properties, in particular the desired values, is approximately 6 minutes, ie a very fast rise and hardening distribution is possible together with very good foam properties.

The mixing and foaming operations are conducted at room temperature, which is within the range of about 15°C to about 40°C. It is preferred to cure the foam at 60 to 100 DEG C. for about 1 to 10 minutes, preferably 2 minutes to achieve sufficient strength or total strength in the resin to hold the form.

Example 1 A foamable resole resin [Lychee 1/lz de
Reichold Canada Limited
Ltd.), manufactured by ES-31-B-2:]
7 phr (resin 100
part per part) of butyrolactone is added semi-continuously.

After that, Rexol*5 phr as a surfactant and Fil as a blowing agent, EON*11 13 phr
f High shear screw type industrial mixer (Canadian Patent No. 1,086, (19) No. 6 1 U.S. Patent No. 4
, 052, 115) to the resin and butyrolactone and 17 pbr of ULTRA-'1'
20 and mix everything. Place the mixture in a metal frame.
Pour into a traveling mold consisting of 1 sheet of Baber facing.
Cure for 2 minutes at 50-170°F. Total processing time is approximately 3
It is a minute. The foamed product was found to have a closed cell content of 86 and a gel time of 65 seconds. Dynate
chR&D Company) Karani-Matic*
The hot water heat transfer test equipment sold as
Value fc after 6 days at ℃ and after 28 days at 100℃
investigate. This value is 0.120 and α122Btu-
in/'F-Lr-ft2.

Examples 2-10 The method of Example 1 is repeated using the proportions of ingredients shown in Table 1. The results are shown in Table 1.

Comparative Example A - The method of Example 1 is repeated without the addition of lactone. The ratios of the components and the results are shown in Table ①. In these closed cell foams, no voids or pinholes are observed in the cell walls, but the strength of the walls, as indicated by the K value, is clearly significantly lower than in the presence of lactone.

Examples 11 to 15 The water content of the resin used was 10 qb and the viscosity was 240
The method of Example 1 was repeated except that it was 00 cps and all other component ratios were changed. HF4
j: ) rather than the luene/xylene sulfonic acid mixture.
Use xylene sulfonic acid.

Check the values after 6 weeks at 25°C. The data and results are shown in Table ■0

[Brief explanation of drawings]

mirror photo,

Claims (21)

[Claims] (1) Improvements include: (a) maintaining the water content of the foamable mixture below 14% by weight; (b) using a resin-soluble acid catalyst; and (c) per 100 parts of resin before foaming. a foaming phenol-aldehyde resin, a blowing agent, characterized in that it consists of adding at least 2 parts of a surfactant to the mixture; and (d) adding a compound of the lactone class to the mixture before foaming; and an acid catalyst, foaming the mixture, and curing the phenolic foam. (2) A further improvement is that the lactone is butyrolactone, 5
- The improved method according to claim 1, characterized in that valerolactone or bromobutyrolactone is used. (3) The improved method according to claim 1, wherein the lactone is butyrolactone. (4) The improved method according to claim 2, wherein the solvent is a mixture of butyrolactone and another solvent. (5) The improved method according to claim 1, characterized in that butyrolactone is added to the resin immediately before foaming. (6) The improved method according to claim 1, characterized in that butyrolactone is added to the catalyst. (7) The amount of butyrolactone is 1 to 100 parts of resin.
The improvement method according to claim 1, characterized in that the amount is 10 parts. (8) The improved method according to claim 4, wherein the other solvent is a polyhydroxy compound. (9) The improved method according to claim 8, wherein the other solvent is ethylene glycol. (10) The improved method according to claim 1, wherein the catalyst is an aromatic sulfonic acid. (11) The catalyst is toluene or xylene sulfonic acid,
The improvement method according to claim 10, characterized in that it is a mixture thereof. (12) The improved method according to claim 11, characterized in that the catalyst is dissolved in ethylene glycol. (13) The improved method according to claim 11, characterized in that the catalyst is dissolved in dimethyl sulfoxide. (14) The improved method according to claim 10, characterized in that the catalyst is used in an amount of 5 to 30 parts per 100 parts of resin. (15) The surfactant is silicone/ethylene oxide/
The improved method according to claim 1, characterized in that the method is selected from the group consisting of propylene oxide copolymers, alkoxysilanes, polysilylphosphonates, polydimethylsiloxanes and polydimethylsiloxane-polyoxyalkylene copolymers. (16) The improved method according to claim 1, wherein the surfactant is a polydimethylsiloxane-polyoxyalkylene block copolymer or ethoxylated castor oil. (17) The amount of surfactant is 2 to 1 per 100 parts of resin.
The improvement method according to claim 1, characterized in that the amount is within the range of 0 parts. (18) The blowing agent is about -40°C to about 93°C at atmospheric pressure.
a polyhalogenated saturated fluorocarbon having a boiling point of
The improvement method according to claim 1, characterized in that the method is selected from the group consisting of halogenated hydrocarbons, hydrocarbons, or mixtures thereof. (19) The blowing agent is 1,1,2-trichloro-1,2,2
-trifluoroethane or trichlorofluoromethane. (20) The improved method according to claim 18 or 19, characterized in that the amount of blowing agent used is about 10 to about 30 parts per 100 parts of resin. (21) Curing of the foamed resin at 60 to 100℃
The improved method according to claim 1, characterized in that the method is carried out for 10 minutes to 10 minutes.